Improvement in refining cast-iron and converting it into steel



UNITED STATES EMILE AND PIERRE E. MARTIN, oF FARIs, FRANCE.

' IMPROVEMENT IN REFINING CAST-IRON AND CONVERTING IT INTO STEEL.

Specification forming part of LettersA Patent No- 72,061, dated December 10, 1867.

To all whom it may concern Be it known that we, EMILE MARTIN an PIERRE EMILE MARTIN, of Paris, in the Empire of France, have invented a new and Improved Method of and Means for Refining and Converting Gast-Iron into Cast-Steel and other metals; and we hereby declare the following to be afull, clear, and exact description of the same.

Our object inv this invention is to manufacture on the sole of a reverberatory furnace, by certain processes hereinafter described, caststeel and its derivatives, of a better quality than can be produced by the processes now in use, eifecting at the same time a greatereconomy in the manufacture or production of said metals.

These processes of manufacture, in affording the means of graduating the proportions of the materials, and of varying the quality of the same during a heating of a mean length of six hours, admit of the following products being obtained:

Hard cast-steel, fitted for the fabrication of cutting-tools, 8vo.; soft cast-steel, (metal homogne,) capable of being welded and wrought or tilted when heated, and of being drawn when cold; cast-iron, possessing the resistance or tenacity of wrought-iron without being subjected to hammering or rolling; mixed metal, adapted to take the place of ordinary iron for moldings or castings, by reason of being better able to withstand concussion or shock.

Our process is based upon the fact that by the high temperature of the metal-bath, (from 1600O to 2000o centigrade,) and by the presence of the oxide of iron mixed with cast-iron, the latter will be deearbureted without the intervention of any air or steam. Thus, the oxide, combined with the high temperature has the same function as the air which is ordinarily blown in. In other words, if, under the induence of a high temperature, the oxide is added to the bath, the iron will be decarbureted; if, on the other hand,castiron is added, the bath will be carbureted.

The economy of our process of refining re- I sults from the simplicity of the operation for reducing the metal to ordinary cast-steel, or homogenous metal, or soft cast-steel capable of being substituted, (with all the advantages which result from its fusibility,) in almost all instances, for wrought or forged iron, which, by the processes now employed, must receive its form from the hand of the workman, or under the stamp or hammer, while by our process the homogeneous metal is only subjected to the two operations of running and rolling or drawing.

The refining is obtained in the course of several hours by meltings or fusions of from three thousand to live thousand kilograms. Under our process we can run in east-steel, homogeneous metal, cast-iron, or mixed metal, 'castings of the greatest weight and dimensions in a single jet, by employing one or more furnaces-an important result, which heretofore has never been realized without heavy expel] Se.

Our process consists in first forming on the sole of a reverberatory furnace, (preferably the Siemens furnace,) to which a basin-like shape is given, a bath of cast or pig iron, which` is brought to a high temperature by being heated for about half an hour. When the bath has been thus heated, ore is thrown in, either roasted, or preferably roasted and cemented, in small pieces of from ten to twentykilogralns in weight, or there may be thrown in pieces of puddled steel, granulated iron, old rails or scrap-iron, (the weight of each being from eight to ten klograms,) which should previously be brought toa clear red or yellow white heat in an adjoining furnace, or in a compartment in the reverberatory furnace especially intended for the purpose. The ore also should be subjectedlto a preliminary heating before being put inthe bath.

The temperature of the furnace during the whole operation is constantly maintained at from 16000. to 2000O centigrade, and the llame is kept at the proper point of intensity by the abundance of the combustible gases. The addition of the ore or pieces of iron, steel, &c., is made at intervals of about twenty minutes, in charges of from one hundred to two hundred kilograms, according to the size of the preliminary bath of cast-iron.

The quality of the material, or the degree to which the bath has been reined, may be determined by a proof 77 that is to say, by a quantity of about five hundred grams,

which is drawn out from the bath in a ladle,

and run into a smallV ingot-mold. When the bath has been refined to the point Where -it p passes to the state of cast-iron, there should be added to it a quantity of cast or pig iron,

preferably manganiferous or specular iron,

and possesses characteristics of its own: First, i the preliminary bath of cast or pig iron;- second, the refining process, carried further than is necessary by the addition of iron or ore;

third, the return of the bath to the point ded sired and sought for, by means of the addition of cast-iron of suitable quality andl weight. Y Y

By varying the doses, we obtain the products hereinbefore named-that is to say:

l. Mixed Metal.-'Proporti'ons of the charge: Preliminary bath of eight hundred kilograms of gray pig-iron; addition of twelve hundred kilograms of iron, steel, or any kind of scrapiron; (the proportion of the iron diminishes With the addition of the ore and the nature or quality of thecast-iron itself;) and iinal addition of six hundred kilograms of cast-iron at the close of the operation.

The product may be rolled or drawn without cracking, and cut at a cherry-red heat with the chisel without becoming hot-short. Bars and castings of this material are without bubbles. A prolonged reheating softens the castings run in mixed metal, and finally completely transforms them into malleable cast- 1ron.

111 order to render the bath entirely homogeneous, a charge or two of iron or ore is reserved for the close of the operation', and the bath is stirred for some moments before runnmg. l

, Duration ofthe operation, five hours; waste, four percent.

Vv2.-"Szfeel for T0oZs.-Proportions of charge: Preliminary bath of eight hundred kilograms of gray pig; addition of thirteen hundred kilograms of steel puddled with the same iron 5 iinal addition of from two hundred to two hundred and fifty kilograms of specular cast-iron, (spiegeleisen fonte.)

Length of operation, six hours; waste, from six to seven per cent.

According to the quality of the cast or pig ,iron employed, the proportion of the diiferent materials employed may be varied as low as two parts of cast-iron and one part of puddled steel and iron, with two hundred kilograms of ore.

3. Homogeneous Metal, or SoftC'a. it-S'teel.-`

ing, and sweating, and are worked readily at all temperatures without becoming hot short.

Proportions of charge: Six hundred kilograms of specular castiron, (spegele'isenfonte;) one thousand kilograms of granulated Vsoft iron, of the same cast-iron 5 one hundred to one hundred and fty kilograms of the same cast-iron at the close of the operation.

Duration` of the operation, seven hours; waste, nine'p'er cent.

4. Gamboa-This is a metal which, when formed into castings, has, without being forged,

y the resistancev or tenacity,'when cold, of

wrought-iron. vIt presents the same species of fractures, and can be rolled and worked at a red or white heat, welding like iron. The fusion of the Vscrap-iron or the puddled steel in the bath, or the refining by the ore, either by itself or mixed with scrap-iron, is carried to the maximum point. As in the preceding operations, so in this case, there is added, at the close of the operation, about iive per cent. of silicious and manganiferous gray pig-iron. The proportion of ive per cent. is augmented as far as twenty per cent. with gray metal made with charcoal or wood, certain qualities vof which metal are refined rapidly, and without being stirred, by the effect alone of the high temperature of the cast-iron bath already obtained.

Duration of the operation, from six to seven hours; waste, twelve per cent.

l The following is an instance of the employment of cast-steel with a large proportion of cast-iron:.()ne thousand kilograms cast-iron, four hundred kilograms scrap-iron, two hundred kilograms ore, and four hundred kilograms cast-iron at the close of the operation.

The following are the proportions of the respective materials when cast-iron and ore are alone employed: One thousand kilograms castiron, and three hundred kilograms roasted manganiferous and oxidated ore. Gast-iron added at the close of the operation-one hundred kilograms for cast-iron, four hundred kilograms `for cast-steel, six hundred kilograms for mixed metal.

Gast-iron granulated or treated according to the processes of Ushatius, Rostaing, or others, may, as above indicated, kbe also employed. In the above instance the oxidated cast-iron assists the refining. Cast-iron amalgamated previously by fusion with ore serves the same purpose. n, In .the drawings accompanying thisl specilication, Figure 1 represents a longitudinal section, and Fig. 2 a transverse section, of our smelting-furnace operating in accordance with the Siemens system.

At A is the door, which, when it becomes necessary to charge the furnace, is opened by means of a suitable tool, which slides on a roller, B. vOn the cast-iron sole C of the furnace is spread a .bed of sand, D, upon which sole. The plate C, as Well as the bed of sand D, extends outside of the Walls ofthe furnace. The running or drawing off of the metal-bath takes place through the hole H.

When it is desired to draw o` the metal, the hole I in the furnace is tapped by suitable means Well known to those skilled-in the art to which this invention pertains. The metal, in a fused state, passes through the hole I, and falls from the opening H into one of the receptacles7 K, mounted on a truck, which is moved upon the rails M M by means of a pinion, O7 and rack P.

Having 110W described our invention, and the Inanner in which the same is or may be metals, substantially as herein shown and de- .I

scribed. Y

In testimony whereof we have signed our names to this specification before two subscribin g witnesses. i

EMILE MARTIN. PIERRE E. MARTIN.

Witnesses C. LAEoND, J. ARMENGAUE. 

